KAIC Rating from Utility Company to Panel

[petersonra]

It is not unusual for provisions that are arbitrary and unnecessary to meet code requirements to be in the boilerplate that makes up specifications. It is still a contract requirement even if it is not a code requirement.

 

[Samardas]

Thanks, Electrofelon. Since the Main Distribution Panel does not have a Main breaker (MLO) and it shows in the existing diagram to be 25KAIC, can I assume the Fault Current is 25KAIC? I am still trying find out the Utility company that services that area of Florida and contact them for the available Fault current, but the original design is so old (1988), that I have a doubt that I will get the rating from the Utility company quickly.

 

[electrofelon]

Thanks, Electrofelon. Since the Main Distribution Panel does not have a Main breaker (MLO) and it shows in the existing diagram to be 25KAIC, can I assume the Fault Current is 25KAIC? I am still trying find out the Utility company that services that area of Florida and contact them for the available Fault current, but the original design is so old (1988), that I have a doubt that I will get the rating from the Utility company quickly.

IT is always a risk to assume, especially an installation from 1988. Although there were AIC and SCCR requirements in the code then, in my experience it was very frequently overlooked back in the 80's and before. Its up to you whether to match what was there or investigate further.

 

[Fred B]

Interesting video of the result of improperly sized SCCR/kAIC installation. As @electrofelon indicated likelihood of the AFC not changing since 1988 rather low.

 

[kwired]

And I treat it as a minimum kAIC rating for additional components if I have no other information about the electrical system.

But every foot of conductor beyond wherever the initial value applies to will reduce the value. How much depends on size and length of conductor.

25 - 50 feet of less than 100 amp conductor will drop an initially high available fault current pretty rapidly.

 

[ggunn]

But every foot of conductor beyond wherever the initial value applies to will reduce the value. How much depends on size and length of conductor.

25 - 50 feet of less than 100 amp conductor will drop an initially high available fault current pretty rapidly.

Of course, but if I don't know the length of the conductors and how they are routed I play it safe. Besides, most of the conductors I deal with are larger than that.

 

[kwired]

Of course, but if I don't know the length of the conductors and how they are routed I play it safe. Besides, most of the conductors I deal with are larger than that.

Well once you go over 200 amp conductors the available fault current doesn't drop as quickly with length, but much of that equipment has higher AIC and withstand ratings as well, and/or has branch devices that are series rated with the main device.